Technical Field
The present disclosure relates to the field of mobile communications devices, and in particular to a method and device for near field communications (NFC).
Description of the Related Art
Mobile telephones and other types of mobile devices are increasingly being equipped with NFC (Near Field Communications) interfaces, which enable them to perform electromagnetic transponder functions over relatively short distances in addition to their other functions. In particular, such devices are able to emulate the functions of an electromagnetic transponder, which could be of the contactless card type, or the contactless reader type. Such functionality for example enhances the mobile device, by allowing it to be used for various applications, for example as an electronic wallet allowing payments to be made and/or by transport applications for accessing services such as transport networks.
To emulate the operation of a contactless card, the mobile device is generally equipped with a contactless front-end integrated circuit (CLF), also called an NFC router. This router is equipped with a radio frequency (RF) transceiver front-end coupled to a low-range antenna to match the communication capabilities of an electromagnetic transponder. In some applications, a secure element (SE) can be used to provide authentication.
In some cases it would be desirable for certain data held by the mobile device to be available even when the mobile device is no longer powered. For example, the host processor of the mobile telephone may be capable of performing card emulation, often referred to as “Host Card Emulation”. However, if the mobile telephone is switched off, or if the battery is totally out of power, Host Card Emulation is not able to work. There is a technical problem permitting data held by the mobile device to be accessible irrespectively of whether or not the mobile device is powered.